The invention disclosed herein involves the processing of multiple channels of electrical signals which are produced by the heart. These channel signals primarily include the ECG signals from body-surface electrodes although signals from electrodes within the body, i.e., intracardiac signals from within vessels and chambers of the heart and epicardial signals from the outer surface of the heart may also be among the cardiac signals processed. Throughout this document, the term “ECG signal” is used to refer to all of these types of channel signals since the inventive method is primarily intended to be used with body-surface electrodes. Such use of terminology is not intended to be limiting to the scope of the invention.
Numerous methods for signal processing of heartbeats are known. Among these are methods disclosed in the following patent applications: PCT International Patent Application No. PCT/US 12/54265 filed on Sep. 7, 2012 and entitled “R-Wave Detection Method;” U.S. patent application Ser. No. 13/842,994 filed on Mar. 15, 2013 and entitled “Multi-Channel Cardiac Measurements;” U.S. patent application Ser. No. 13/888,070 filed on May 5, 2013 and entitled “Multi-Channel Cardiac Measurements;” and U.S. patent application Ser. No. 13/922,953 filed on Jun. 20, 2013 and entitled “Multi-Channel Cardiac Measurements.” Each of these applications are in whole or in part invented by the inventor of the present invention and are commonly owned by APN Health, LLC of Pewaukee, Wis. None of these applications combine signals of multiple cardiac channels in the heartbeat detection process prior to performing a threshold comparison. None of these inventions includes steps which categorize the detected heartbeats into categories having similar heartbeat morphologies or shapes.
Other current technology which involves heartbeat detection and categorization relates to systems for post-processing of ECG signals captured by a Holter monitor. These systems typically involve the processing of ECG signals using values of such signals at more than one point in time within an individual heartbeat. In contrast, the present invention depends on measurements at a single instant in time in order to detect and categorize heartbeats, allowing this inventive system to detect heartbeats very early in the time period of the heartbeat and to operate essentially in real time.
Categorizing heartbeats into groups having similar morphologies in essentially real time enables a cardiologist to very quickly identify the frequency of occurrence of various ectopic heartbeats, particularly for patients undergoing interventional procedures to alleviate the causes of such heartbeats. Among the ectopic heartbeats which are of importance are: premature ventricular contractions (PVC); premature atrial contractions (PAC); various types of bundle branch blocks; ventricular escape beats; junctional escape beats; fusion beats; and paced beats.
PVC and PAC heartbeats (also known by several other names) are among the most common ectopic heartbeats and when they occur as individual beats rather than in a series of repetitive beats, are not considered to be clinically significant. Such individual beats commonly occur in healthy young and elderly patients without heart disease. However, when ectopic beats recur on a much more regular basis, interventional treatment or procedures may be undertaken to alleviate such cardiac abnormalities. The present invention is an important advance in the technology of cardiac diagnosis and treatment by providing a rapid and reliable method for heartbeat detection and categorization.